1. Field of the Invention
The present invention relates to an application machine for staking contacts, e.g. circuit board pins, in holes in a circuit board, and particularly relates to an improved control system for such an application machine.
2. Description of the Prior Art
An application machine for mounting wire wrap pins on circuit boards is described in U.S. Pat. No. 3,605,237. In the application machine described in this patent, a carrier strip on which circuit board pins are spaced at regular intervals is indexed to position the lead pin between a pair of clamps and in approximate axial alignment with a long, thin punch. A carrier strip feed track extends from a feed mechanism to one of the clamps. A pivoted portion of the feed track connects the thick portion of the track with a moveable clamp portion so the strip is moved as the clamp moves. After the pin has been positioned between the clamp, the punch lowers and the clamp closes to engage the pin and hold it in exact axial alignment with the punch. The punch then moves toward the pin to engage the pin and the clamps are opened to permit further movement of the punch to mount the pins in a hole in a circuit board positioned on a moveable support below the punch. A staking anvil mounted below the moveable support is extended in alignment with the punch to support the circuit board adjacent the hole in the circuit board during staking of the pin.
In the application machine described in this patent, the circuit board pin is accurately aligned relative to the punch, picked up by the punch, removed from the carrier strip and secured to the circuit board during a single downward stroke of the punch. Performing all these functions as the punch moves from the retracted to the fully extended position permits the applicator to attach pins to a circuit board at a high rate of speed. The operations of orienting, severing, releasing and staking the pins are all tied to the motion of the punch so that it is not possible for these steps to be performed out of sequence, and jamming is reduced. However, in the event the hole for receiving the contact in the circuit board is not properly aligned with the punch and anvil in the support, or in the event a contact has already been staked in the hole in the circuit board, the punch will attempt to stake another contact in a hole in which a contact is already present.
The improved control system of the present invention provides for insuring a hole in a circuit board is present and clear for receiving a circuit board pin.
An apparatus for direct insertion into a substrate of terminals from a flexible carrier strip is described in U.S. Pat. No. 3,837,063. In this apparatus, an anvil assembly cooperates with a sensor and an indicator to insure correct substrate orientation relative to a ram assembly. In this apparatus, ram activation is prevented unless an anvil finger is properly received in a terminal-receiving aperture.
A machine for successively positioning a workpiece such as a circuit board in predetermined relation to a tool such as an inserter according to a program dictated for instance by a template is described in U.S. Pat. No. 3,641,651. The machine includes a stylus in communication with a fluidic sensor, and the stylus is alignable with holes in a template so the fluidic sensor controls one or more component inserting heads.
The anvil assembly of the aforementioned patent uses a spring loaded mechanical finger mounted on a stationary staking anvil to prevent activation of a terminal-inserting ram unless a clear circuit board hole is present. Although this satisfactorily prevents staking a terminal where no hole is present, or double staking where a terminal has already been staked, such a mechanical finger is unsuitable where the application machine uses an extendable ram, e.g. such a mechanical finger can damage the circuit board or circuit board hole if minor misalignment occurs, or can dislodge a pin already staked when an anvil is extended to support the circuit board.
In the machine for positioning a circuit board of the latter mentioned patent, the stylus in communication with the fluidic sensor is alignable with holes in a template not with the contact inserting head or anvil. In this configuration, the sensor does not insure the actual hole in the circuit board is in proper alignment for receiving a contact, nor does it positively prevent double staking of a contact in a hole in a circuit board in which a contact has already been staked.
The improved control system of the present invention insures proper alignment of an extendable staking anvil with a hole for receiving a contact in a circuit board and positively prevents double staking of a contact in a hole in the circuit board in which a contact has already been staked.